4mm Neoprene cover designed to insulate and protect the downtube battery from inclement weatherProtection against the elements while riding or transporting on a car rackInsulates battery to help operate more efficientlyIntegrated pocket holds a phone, keys or walletFits batteries 3.5` to 4.5` in diameterVelcroMediumBlackUPC/EAN/GTIN: 859402006949